When drilling for oil and gas, a wellbore or borehole of an oil or gas well is typically drilled from surface to a first depth and lined with a steel casing. The casing is located in the wellbore extending from a wellhead provided at surface or seabed level, and is then cemented in place. Following testing and other downhole procedures, the borehole may be extended to a second depth and a further section of casing is installed and cemented in place. This process may be repeated until the borehole has been extended to a location where it intersects a producing formation.
Drilling, production and completion of offshore wells from a floating platform, e.g., a vessel, tension leg platform, etc. may be conducted through a riser assembly which extends from the platform to the wellhead at the seabed level. The riser assembly includes a series of pipe sections connected end to end. Marine drilling risers provide a conduit through which materials may flow between the platform and the wellbore.
Marine managed pressure drilling may include wellbore pressure control devices, e.g., devices known as rotating control devices, rotating diverters, rotating blowout preventers (hereinafter, rotating control device or “RCD”), disposed at a selected position along the length of the riser assembly. Such pressure control devices are configured to enable a string of pipe and/or wellbore drilling or intervention tools to sealingly pass there through axially, and further to enable rotation of the pipe while sealing the wellbore hydraulically. When used, for example in wellbore drilling operations, a drill pipe string is passed through a bearing assembly in the RCD. The bearing assembly enables a sealing element therein and the pipe to rotate relative to a housing that may be affixed to the top of a casing or other pipe disposed at least partially into the wellbore. The housing is configured to enable hydraulic communication to the interior of the wellbore below the bearing assembly.
When bearings, seals, or other elements in the bearing assembly fail, expensive and difficult procedures to remove the pipe from the wellbore may be conducted while maintaining the wellbore hydraulic seal through the RCD.